Polyesters which incorporate poly(alkylene ether) glycols are well known within the art. Said polyesters are typically produced by adding the poly(alkylene ether)glycols at the beginning of the polyester polymerization stage. For example, Shivers, in U.S. Pat. No. 3,023,192, teaches the production of segmented copolyetherester elastomers, which incorporate poly(alkylene ether)glycols, by adding the poly(ethylene glycol) to dimethyl terephthalate, ethylene glycol and catalysts followed by polymerization. Further art teachings of similar production processes include, for example, U.S. Pat. Nos. 3,243,413, 3,558,557, 3,651,014, 3,701,755, 3,763,109, 3,766,146, 3,784,520, 3,880,976, 4,136,715, 4,262,114, 4,315,882, 4,467,595, 4,670,498, 4,906,729, and 4,906,714.
Occasionally, it has been generally taught that the poly(alkylene ether)glycol may be added to the polyester and incorporated through reesterification. For example, Frohlich, et al., in U.S. Pat. No. 3,663,653 teach that xe2x80x9cAnother possibility of preparing the block copolyesters of the invention consists in admixing the polytetrahydrofurandiol to the polyester melt. Owing to a reesterification reaction the polytetrahydrofuran blocks are bound to the polyester through their hydroxyl terminal groups.xe2x80x9d (U.S. Pat. No. 3,663,653, column 2, lines 6-10). As an additional example, Wolfe, in U.S. Pat. No. 3,775,374, teaches that xe2x80x9cSuch prepolymers can also be prepared by a number of alternative esterification of ester interchange processes; for example, the long chain glycol can be treated with a high or low molecular weight short chain ester homopolymer or copolymer in the presence of catalyst until randomization occurs.xe2x80x9d (U.S. Pat. No. 3,775,374, column 4, lines 40-45). A similar teaching may be found by Hoeschele as taught in U.S. Pat. No. 3,801,547. As a further example, Buxbaum, et al., in U.S. Pat. Nos. 4,156,774 and 4,315,882, teach, xe2x80x9cHowever, it is also possible to follow a procedure such that block polyesters are obtained by, for example, subjecting precondensates of homopolyesters (for example polyethylene terephthalate and polydiethylene glycol terephthalate) in appropriate quantity ratios to a polycondensation reaction, specifically on their own or together with a polyester of terephthalic acid and polybutylene glycolxe2x80x9d. As yet a further example, Tanaka, et al., in U.S. Pat. No. 4,251,652, teach that such polyesters may be prepared by xe2x80x9cpolycondensing at a temperature of from 210 to 270xc2x0 C. at least one dicarboxylic acid and at least one diol to provide a polyester and then polycondensing the resultant polyester with TERATHANE(copyright) at a temperature from 200 to 250xc2x0 C.xe2x80x9d. Nelsen, in U.S. Pat. No. 4,355,155, teaches that xe2x80x9cthe long chain glycol can be reacted with a high or low molecular weight short chain ester homopolymerxe2x80x9d. Greene, in U.S. Pat. No. 5,128,185, teaches xe2x80x9cFor example, long chain glycol can be reacted with high or low molecular weight short chain ester homopolymer or copolymer in the presence of catalyst until randomization occurs.xe2x80x9d However, none of these references exemplify such processes within their disclosures. They exemplify production processes through the monomeric species, as discussed above.
Rarely, it has been exemplified within the background art to produce said polyesters which incorporate poly(alkylene ether)glycols from the interaction of preformed polyesters with the poly(alkylene ether)glycols. For example, Still, et al., in U.S. Pat. Nos. 4,968,778 and 4,970,275, teach a process to produce polyesters which incorporate poly(alkylene ether)glycols which consists xe2x80x9cof a low molecular weight polyester formed by the reaction of terephthalic acid and ethylene glycol (1:1.4 TA:EG)xe2x80x9d combined with a poly(alkylene glycol)ether and catalysts followed by heating and finishing.
Takanoo, et al., in U.S. Pat. No. 5,331,066, teaches a process for the production of polyesters which incorporate poly(alkylene ether)glycols which comprises conducting polycondensation after or while melting and mixing a polyester polymer of 0.5 dL/g or more intrinsic viscosity and a polyether polymer having hydroxy groups at its terminals and having a number average molecular weight of 200 to 10,000. However, they further teach that xe2x80x9cIf the quantity of polyether is below one part by weight, desired polymer properties cannot be obtained, and if it is above 60 parts by weight, polyether extremely deteriorates and lowers in quality.xe2x80x9d
The present invention overcomes the shortcomings of the background art and provides a process to produce polyesters which incorporate 1 to 90 weight percent poly(alkylene ether)glycols while maintaining adequate thermal properties.
The present invention provides a process for producing a polyester that comprises 1 to 90 wt. % poly(alkylene ether) glycol. The process comprises the step of copolymerizing (i) a preformed polyester polymer having an inherent viscosity of at least 0.4 dL/g, (ii) a poly(alkylene ether) glycol, and (iii) a dicarboxylic acid or anhydride, to obtain a polyester comprising 1 to 90 wt. % poly(alkylene ether glycol).
In one embodiment of the invention, the dicarboxylic acid comprises an unsubstituted or substituted aromatic, aliphatic, unsaturated, or alicyclic dicarboxylic acid having from 2 carbon atoms to 36 carbon atoms. In another embodiment, the anhydride comprises an unsubstituted or substituted aromatic, aliphatic, unsaturated, or alicyclic dicarboxylic anhydride having from 2 carbon atoms to 36 carbon atoms. In yet another embodiment of the invention, the dicarboxylic acid or anhydride has a concentration of 0.1 to 2 molar stoichiometric equivalents of said poly(alkylene ether) glycol.
In another embodiment, the process of the invention includes mixing and heating preformed polyesters with poly(alkylene ether) glycols and dicarboxylic acids or anhydrides, followed by standard finishing processes. The as produced polyesters which incorporate poly(alkylene ether)glycols of the present invention have been found to maintain comparable thermal stability to those produced by background art processes while emitting substantially less volatile organic compound byproducts.
It has become increasingly understood that there is a need to reduce the environmental footprint of chemical processes. In typical art polyester polymerizations, excesses of the glycol are used and, in turn, must be recovered and repurified. For example, for poly(ethylene terephthalate), generally 40 to 100 percent excess ethylene glycol are used. For poly(1,4-butylene terephthalate) and poly(1,3-propylene terephthalate), the excess glycol utilized is typically in the range from about 20 to 60 percent. In addition, for polyester polymerizations which start from dimethyl terephthalate, as is typical for the preparation of polyesters which incorporate poly(alkylene ether)glycols, significant quantities of methanol must also be recovered and recycled. Such polymerization processes for polyesters which incorporate poly(alkylene ether)glycols are taught within the art in, for example, U.S. Pat. Nos. 3,023,192, 3,243,413, 3,558,557, 3,651,014, 3,701,755, 3,763,109, 3,766,146, 3,784,520, 3,880,976, 4,136,715, 4,262,114, 4,315,882, 4,467,595, 4,670,498, 4,906,729, 4,906,714.
As a means to reduce the amount of volatile organic compounds (VOC) evolved within the processes to produce polyesters which incorporate poly(alkylene ether)glycols, it has been generally taught within the art to start with preformed polyesters. Such general teachings may be found within, for example, U.S. Pat. Nos. 3,663,653, 3,775,374, 3,801,547, 4,156,774, 4,251,652, 4,315,882, 4,355,155 and 5,128,185, said references are hereby incorporated into the present invention through reference. These references do not exemplify said process and therefore are not enabling to one skilled within the art. The use of preformed low molecular weight polyesters in the production of polyesters which incorporate poly(alkylene ether) glycols was taught within U.S. Pat. Nos. 4,968,778 and 4,970,275.
The use of high molecular weight polyesters with intrinsic viscosities of 0.50 dL/g or greater in the production of polyesters which contain 1 to 60 parts by weight, preferably 5 to 35 parts by weight, of poly(alkylene ether)glycols was taught within U.S. Pat. No. 5,331,066, which is hereby incorporated into the present invention by reference. They however strongly teach away from the use of this process in the production of polyesters which incorporate greater than 60 weight percent poly(alkylene ether)glycols due to degradation of the thermal properties.
The present invention has surprisingly found a process to produce polyesters which incorporate between about 1 and 90 weight percent poly(alkylene ether)glycols which significantly reduces the level of volatile organic compound byproducts while maintaining thermal stabilities comparable to similar materials made within the art.
One aspect of the present invention is a process to produce polyesters which incorporate between about 1 to 90 weight percent poly(alkylene ether) glycols. Said process includes mixing and heating preformed polyesters with poly(alkylene ether) glycols and dicarboxylic acids or anhydrides, followed by standard finishing processes.
Said preformed polyester starting materials of the present invention are essentially comprised of 48 to 50 mole percent of one or more dicarboxylic acids, 48 to 50 mole percent of one or more diols and 0 to 2 mole percent polyfunctional branching agents.
Said dicarboxylic acid component is meant to include unsubstituted and substituted aromatic, aliphatic, unsaturated, and alicyclic dicarboxylic acids and the lower alkyl esters of dicarboxylic acids having from 2 carbons to 36 carbons. Specific examples of the desirable dicarboxylic acid component include terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,6-napthalene dicarboxylic acid, dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid, dimethyl-2,7-naphthalate, 3,4xe2x80x2-diphenyl ether dicarboxylic acid, dimethyl-3,4xe2x80x2diphenyl ether dicarboxylate, 4,4xe2x80x2-diphenyl ether dicarboxylic acid, dimethyl-4,4xe2x80x2-diphenyl ether dicarboxylate, 3,4xe2x80x2-diphenyl sulfide dicarboxylic acid, dimethyl-3,4xe2x80x2-diphenyl sulfide dicarboxylate, 4,4xe2x80x2-diphenyl sulfide dicarboxylic acid, dimethyl-4,4xe2x80x2-diphenyl sulfide dicarboxylate, 3,4xe2x80x2-diphenyl sulfone dicarboxylic acid, dimethyl-3,4xe2x80x2-diphenyl sulfone dicarboxylate, 4,4xe2x80x2-diphenyl sulfone dicarboxylic acid, dimethyl-4,4xe2x80x2-diphenyl sulfone dicarboxylate, 3,4xe2x80x2-benzophenonedicarboxylic acid, dimethyl-3,4xe2x80x2-benzophenonedicarboxylate, 4,4xe2x80x2-benzophenonedicarboxylic acid, dimethyl-4,4xe2x80x2-benzophenonedicarboxylate, 1,4-naphthalene dicarboxylic acid, dimethyl-1,4-naphthalate, 4,4xe2x80x2-methylene bis(benzoic acid), dimethyl-4,4xe2x80x2-methylenebis(benzoate), oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinc acid, glutaric acid, dimethyl glutarate, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, dimethyl adipate, 3-methyladipic acid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, dimer acid, 1,4-cyclohexanedicarboxylic acid, dimethyl-1,4-cyclohexanedicarboxylate, 1,3-cyclohexanedicarboxylic acid, dimethyl-1,3-cyclohexanedicarboxylate, 1,1-cyclohexanediacetic acid, metal salts of 5-sulfo-dimethylisophalate, fumaric acid, maleic anhydride, maleic acid, hexahydrophthalic acid phthalic acid and the like and mixtures derived therefrom. This should not be considered limiting. Essentially any dicarboxylic acid known within the art may find utility within the present invention.
Said diol component is meant to include unsubstituted, substituted, straight chain, branched, cyclic aliphatic, aliphatic-aromatic or aromatic diols having from 2 carbon atoms to 36 carbon atoms and poly(alkylene ether) glycols with molecular weights between about 250 to 4,000. Specific examples of the desirable other glycol component include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, isosorbide, dimer diol, 4,8-bis(hydroxymethyl)-tricyclo[5.2.1.0/2.6]decane, 1,4-cyclohexanedimethanol, di(ethylene glycol), tri(ethylene glycol), poly(ethylene ether) glycols, poly(butylene ether) glycols and the like and mixtures derived therefrom. This should not be taken as limiting. Essentially any diol known within the art may find use within the present invention.
Said polyfunctional branching agent is meant to include any material with three or more carboxylic acid functions, hydroxy functions or a mixture thereof. The term xe2x80x9ccarboxylic acid functionsxe2x80x9d is meant to include carboxylic acids, lower alkyl esters of carboxylic acids, glycolate esters of carboxylic acids, and the like and mixtures thereof. Specific examples of the desirable polyfunctional branching agent component include 1,2,4-benzenetricarboxylic acid, (trimellitic acid), trimethyl-1,2,4-benzenetricarboxylate, tris(2-hyroxyethyl)-1,2,4-benzenetricarboxylate, trimethyl-1,2,4-benzenetricarboxylate, 1,2,4-benzenetricarboxylic anhydride, (trimellitic anhydride), 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, (pyromellitic acid), 1,2,4,5-benzenetetracarboxylic dianhydride, (pyromellitic anhydride), 3,3xe2x80x2,4,4xe2x80x2-benzophenonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, citric acid, tetrahydrofuran-2,3,4,5-tetracarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, pentaerythritol, 2-(hydroxymethyl)-1,3-propanediol, 2,2-bis(hydroxymethyl)propionic acid, trimer acid, and the like and mixtures therefrom. This should not be considered limiting. Essentially any polyfunctional material which includes three or more carboxylic acid or hydroxyl functions may find use within the present invention.
Preferably the preformed polyester starting material of the present invention is selected from the group comprised of poly(ethylene terephthalate), poly(1,3-propylene terephthalate), (poly(trimethylene terephthalate)), and poly(1,4-butylene terephthalate).
The preformed polyesters of the present invention need to have an inherent viscosity, which is an indicator of molecular weight, greater than about 0.40 dL/g. More desirably, the inherent viscosity (IV) of said preformed polyesters will be greater than about 0.50 dL/g, as measured on a 0.5 percent (weight/volume) solution of the polyester in a 50:50 (weight) solution of trifluoroacetic acid:dichloromethane solvent system at room temperature. These inherent viscosities will be sufficient for use within the process of the present invention.
The preformed polyester starting materials of the present invention may be prepared by conventional polycondensation techniques. The product compositions may vary somewhat based on the method of preparation used, particularly in the amount of diol that is present within the polymer. These methods include the reaction of the diol monomers with acid chlorides. For example, acid chlorides of the dicarboxylic acid component may be combined with the diol component in a solvent, such as toluene, in the presence of a base, such as pyridine, which neutralizes the hydrochloric acid as it is produced. Such procedures are known. See, for example, R. Storbeck, et al., in J. Appl. Polymer Science, Vol. 59, pp. 1199-1202 (1996). Other well known variations using acids chlorides may also be used, such as the interfacial polymerization method, or the monomers may simply be stirred together while heating.
When the polymer is made using acid chlorides, the ratio of the monomer units in the product polymer is about the same as the ratio of reacting monomers. Therefore, the ratio of monomers charged to the reactor is about the same as the desired ratio in the product. A stoichiometric equivalent of the diol components and the diacid components generally will be used to obtain a high molecular weight polymer.
Preferably, the preformed polyesters of the present invention will be produced through a melt polymerization method. In the melt polymerization method, the dicarboxylic acid component, (either as acids, esters, or mixtures thereof) the diol component and the polyfunctional branching agent, are combined in the presence of a catalyst to a high enough temperature that the monomers combine to form esters and diesters, then oligomers, and finally polymers. The polymeric product at the end of the polymerization process is a molten product. Generally, the diol component is volatile and distills from the reactor as the polymerization proceeds. Such procedures are known. See, for example, U.S. Pat. Nos. 3,563,942, 3,948,859, 4,094,721, 4,104,262, 4,166,895, 4,252,940, 4,390,687, 4,419,507, 4,585,687, 5,053,482, 5,292,783, 5,446,079, 5,480,962, and 6,063,464 and the references cited therein, which are herein incorporated by reference.
The melt process conditions of the present invention, particularly the amounts of monomers used, depend on the polymer composition that is desired. The amount of the diol component, dicarboxylic acid component, and branching agent are desirably chosen so that the final polymeric product contains the desired amounts of the various monomer units, desirably with equimolar amounts of monomer units derived from the respective diol and diacid components. Because of the volatility of some of the monomers, especially some of the diol components, and depending on such variables as whether the reactor is sealed, (i.e., is under pressure), the polymerization temperature ramp rate, and the efficiency of the distillation columns used in synthesizing the polymer, some of the monomers may need to be included in excess at the beginning of the polymerization reaction and removed by distillation as the reaction proceeds. This is particularly true of the diol component.
The exact amount of monomers to be charged to a particular reactor is readily determined by a skilled practitioner, but often will be in the ranges below. Excesses of the diacid and diol are often desirably charged, and the excess diacid and diol is desirably removed by distillation or other means of evaporation as the polymerization reaction proceeds. The diol component is desirably charged at a level 0 to 100 percent greater than the desired incorporation level in the final product. For examples of the diol component which are volatile under the polymerization conditions, such as ethylene glycol, 1,3-propanediol, or 1,4-butanediol, 30 to 100 percent excesses are desirably charged. For less volatile examples of the diol component, such as dimer diol, no excesses need be desirably charged.
The ranges given for the monomers are very wide because of the wide variation in the monomer loss during polymerization, depending on the efficiency of distillation columns and other kinds of recovery and recycle systems and the like, and are only an approximation. Exact amounts of monomers that are charged to a specific reactor to achieve a specific composition are readily determined by a skilled practitioner.
In the polymerization process, the monomers are combined, and are heated gradually with mixing with a catalyst or catalyst mixture to a temperature in the range of 230xc2x0 C. to about 300xc2x0 C., desirably 250xc2x0 C. to 295 xc2x0 C. The exact conditions and the catalysts depend on whether the diacids are polymerized as true acids or as dimethyl esters. The catalyst may be included initially with the reactants, and/or may be added one or more times to the mixture as it is heated. The catalyst used may be modified as the reaction proceeds. The heating and stirring are continued for a sufficient time and to a sufficient temperature, generally with removal by distillation of excess reactants, to yield a molten polymer having a high enough molecular weight to be suitable for the present invention.
Catalysts that may be used include salts of Li, Ca, Mg, Mn, Zn, Pb, Sb, Sn, Ge, and Ti, such as acetate salts and oxides, including glycol adducts, and Ti alkoxides. These are generally known in the art, and the specific catalyst or combination or sequence of catalysts used may be readily selected by a skilled practitioner. The preferred catalyst and preferred conditions differ depending on, for example, whether the diacid monomer is polymerized as the free diacid or as a dimethyl ester and the exact chemical identity of the diol component.
Said poly(alkylene ether)glycols of the present invention may have a molecular weight in the range of about 500 to about 4000. Specific examples of poly(alkylene ether)glycols useful within the present invention include, for example, poly(ethylene glycol), poly(1,3-propylene glycol), poly(1,4-butylene glycol), (polytetrahydrofuran), poly(pentmethylene glycol), poly(hexamethylene glycol), poly(hepthamethylene glycol), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), 4,4xe2x80x2-isopropylidenediphenol ethoxylate (Bisphenol A ethoxylate), 4,4xe2x80x2-(1-phenylethylidene)bisphenol ethoxylate (Bisphenol AP ethoxylate), 4,4xe2x80x2-ethylidenebisphenol ethoxylate (Bisphenol E ethoxylate), bis(4-hydroxyphenyl)methane ethoxylate (Bisphenol F ethoxylate), 4,4xe2x80x2-(1,3-phenylenediisopropylidene)bisphenol ethoxylate (Bisphenol M ethoxylate), 4,4xe2x80x2-(1,4-phenylenediisopropylidene)bisphenol ethoxylate (Bisphenol P ethoxylate), 4,4xe2x80x2-sulfonyidiphenol ethoxylate (Bisphenol S ethoxylate), 4,4xe2x80x2-cyclohexylidenebisphenol ethoxylate (Bisphenol Z ethoxylate),
and the like and mixtures thereof. This should not be considered limiting. Essentially any poly(alkylene ether)glycols known within the art may find use in the process of the present invention.
The amount of poly(alkylene ether)glycol to be added in the process of the present invention may be in the amount necessary to produce polyesters which incorporate 1 to 90 weight percent poly(alkylene ether)glycol. Preferably, the amount of poly(alkylene ether)glycol to be added in the process of the present invention may be in the amount necessary to produce polyesters which incorporate 5 to 85 weight percent poly(alkylene ether)glycol. More preferably, the amount of poly(alkylene ether)glycol to be added in the process of the present invention may be in the amount necessary to produce polyesters which incorporate 8 to 80 weight percent poly(alkylene ether)glycol.
Said dicarboxylic acid or anhydride component is meant to include unsubstituted and substituted aromatic, aliphatic, unsaturated, and alicyclic dicarboxylic acids having from 2 carbons to 36 carbons and unsubstituted and substituted aromatic, aliphatic, unsaturated, and alicyclic dicarboxylic anhydrides having from 2 carbons to 36 carbons. Specific examples of the desirable dicarboxylic acid or anhydride component include terephthalic acid, isophthalic acid, 2,6-napthalene dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 3,4xe2x80x2-diphenyl ether dicarboxylic acid, 4,4xe2x80x2-diphenyl ether dicarboxylic acid, 3,4xe2x80x2-diphenyl sulfide dicarboxylic acid, 4,4xe2x80x2-diphenyl sulfide dicarboxylic acid, 3,4xe2x80x2-diphenyl sulfone dicarboxylic acid, 4,4xe2x80x2-diphenyl sulfone dicarboxylic acid, 3,4xe2x80x2-benzophenonedicarboxylic acid, dimethyl-3,4xe2x80x2-benzophenonedicarboxylate, 4,4xe2x80x2-benzophenonedicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 4,4xe2x80x2-methylene bis(benzoic acid), oxalic acid, malonic acid, succinic acid, methylsuccinc acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, 3-methyladipic acid, 2,2,5,5-tetramethylhexanedioic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, dimer acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,1-cyclohexanediacetic acid, metal salts of 5-sulfo-isophthalic acid, fumaric acid, maleic anhydride, maleic acid, hexahydrophthalic acid, phthalic acid, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride, 1,8-naphthalic anhydride, 2,3-napthalic anhydride and the like and mixtures derived therefrom. This should not be considered limiting. Essentially any dicarboxylic acid and anhydride known within the art may find utility within the present invention.
The dicarboxylic acid or anhydride component should be added at a level between 0.10 to 2.0 molar stoichiometric equivalents of the poly(alkylene ether)glycol component. Preferably, the dicarboxylic acid or anhydride component should be added at a level between 0.10 to 1.25 molar stoichiometric equivalents of the poly(alkylene ether)glycol component. More preferably, the dicarboxylic acid or anhydride component should be added at essentially molar stoichiometric equivalence of the poly(alkylene ether)glycol component.
The process of the present invention includes mixing together the preformed polyester, the poly(alkylene ether)glycol, and the dicarboxylic acid or anhydride at a sufficient temperature and for a sufficient time to form the polyesters which incorporate poly(alkylene ether)glycols of the present invention followed by a second finishing process to enhance the molecular weight of the polyester of the present invention.
The temperature utilized within the process of the present invention should be sufficient to melt the preformed polyester and to allow for a significant reaction rate between the preformed polyester, the poly(alkylene ether)glycol, and the dicarboxylic acid or anhydride. Generally, the process temperature of the present invention will be within the range of 150xc2x0 C. to 350xc2x0 C. Preferably, this process temperature range is between about 220xc2x0 C. and 300xc2x0 C.
The time required for the process of the present invention will be a complicated function of the exact chemical identity of the preformed polyester, the exact chemical identity of the poly(alkylene ether)glycol, the exact chemical identity of the dicarboxylic acid or anhydride, the process temperature, the process equipment utilized, the mixing intensity, and the like. An effective amount of time is required by the process of the present invention to provide the products of the present invention. The time for the process of the present invention may be in the range from 0 to about 5 hours. Generally, the process of the present invention will have a time greater than one minute. Preferably, the process time will be greater than 5 minutes. More preferably, the process time will be greater than 20 minutes.
Optionally, added catalysts may be used within the process of the present invention. It has generally been found that the process of the present invention may be performed relying on the residual catalysts incorporated within the preformed polyester. However, it is contemplated that the use of additional catalysts will increase the rate of the process, if that is desired. Additional catalysts that may be used include salts of Li, Ca, Mg, Mn, Zn, Pb, Sb, Sn, Ge, and Ti, such as acetate salts and oxides, including glycol adducts, and Ti alkoxides. These are generally known in the art, and the specific catalyst or combination or sequence of catalysts used may be readily selected by a skilled practitioner.
The process may be performed in any known equipment in the art. For example, the preformed polyester, the poly(alkylene ether)glycols, the dicarboxylic acid or anhydride, and optionally, additional catalysts, may be added to a stirred autoclave and heated to melt said preformed polyester, poly(alkylene ether)glycol, and dicarboxylic acid or anhydride, and mixed at temperature for a sufficient time to effect the process. However, it is further contemplated that the preformed polyester, the poly(alkylene ether)glycol, the dicarboxylic acid or anhydride, and optionally, additional catalysts, may be fed to a single- or twin-screw extruder, melted and mixed and, in turn, fed to a transfer line to allow for sufficient time to effect the process of the present invention. Said transfer line may include additional mixing, as through static mixers. Alternatively, the molten mixture exiting the extruder may be fed to a continuous polymerizer (CP) multi-vessel train. Each vessel would constitute a continuous stirred reactor (CSR). This should not be considered limiting. Essentially any equipment known within the art which allows for process of the present invention will find utility within the present invention.
Preferentially, the process of the present invention includes finishing the as produced product to achieve the desired product molecular weight. This may be performed by sparging the molten product with inert gases, such as nitrogen, or by applying vacuum. Heating under the inert gas sparging or vacuum may be continued until the molten polymer reaches the desired molecular weight, usually recognized by an increase in the melt viscosity to a pre-determined level. This is observed as an increase in the torque needed for the stirring motor to maintain stirring. An inherent viscosity of at least 0.5 dL/g, and generally up to about 0.65 dL/g or greater can be achieved by this melt finishing process without further efforts at raising molecular weight.
Optionally, solid state polymerization may be used to achieve the higher inherent viscosities (molecular weights).
The product made by the process of the present invention, after extruding, cooling and pelletizing, may be essentially noncrystalline. Noncrystalline material can be made semicrystalline by heating it to a temperature above the glass transition temperature for an extended period of time. This induces crystallization so that the product can then be heated to a higher temperature to raise the molecular weight.
The polymer may also be crystallized prior to solid state polymerization by treatment with a relatively poor solvent for polyesters which induces crystallization. Such solvents reduce the glass transition temperature (Tg) allowing for crystallization. Solvent induced crystallization is known for polyesters and is described in U.S. Pat. Nos. 5,164,478 and 3,684,766, which are incorporated herein by reference.
The semicrystalline polymer is subjected to solid state polymerization by placing the pelletized or pulverized polymer into a stream of an inert gas, usually nitrogen, or under a vacuum of 1 Torr, at an elevated temperature, but below the melting temperature of the polymer for an extended period of time.
The polyesters which incorporate poly(alkylene ether)glycols produced by the process of the present invention may incorporate additives, fillers, or other materials commonly taught within the art. Said additives may include thermal stabilizers, antioxidants, UV absorbers, UV stabilizers, processing aides, waxes, lubricants, color stabilizers, and the like. Said fillers may include calcium carbonate, glass, kaolin, talc, clay, carbon black, and the like. Said other materials may include nucleants, pigments, dyes, delusterants, such as titanium dioxide and zinc sulfide, antiblocks, such as silica, antistats, flame retardants, brighteners, silicon nitride, metal ion sequestrants, anti-staining agents, silicone oil, surfactants, soil repellants, modifiers, viscosity modifiers, zirconium acid, reinforcing fibers, and the like. These additives, fillers, and other materials may be incorporated within the polyesters which incorporate poly(alkylene ether)glycol of the present invention through a separate melt compounding process utilizing any known intensive mixing process, such as extrusion, through intimate mixing with the solid granular material, such as pellet blending, or through cofeeding within the process of the present invention. Alternatively, the additives, fillers, and other materials may be incorporated into the preformed polyester starting material prior to the process of the present invention. If said additives, fillers, and other materials are incorporated prior to or during the process of the present invention, it is important to ensure that they do not interfere with the process of the present invention.
The polyesters which incorporate poly(alkylene ether)glycols produced by the process of the present invention may be blended with other polymers commonly taught within the art. Said other polymers may include polyolefins, such as polyethylene, polypropylene, polybutene, poly-4-methyl pentene, polystyrene, and the like, cyclic olefin polymers, modified polyolefins, such as copolymers of various alpha-olefins, glycidyl esters of unsaturated acids, ionomers, ethylene/vinyl copolymers such as ethylene/vinyl chloride copolymers, ethylene/vinyl acetate copolymers, ethylene/acrylic acid copolymers, ethylene/methacrylic acid copolymers and the like, thermoplastic polyurethanes, polyvinyl chloride, polyvinlidene chloride copolymers, liquid crystalline polymers, fluorinated polymers, such as polytetrafluoroethylene, ethylene tetrafluoroethylene copolymers, tetrafluoroethylene hexafluoropropylene copolymers, polyfluoroalkoxy copolymers, polyvinylidene fluoride, polyvinylidene copolymers, ethylene chlorotrifluoroethylene copolymers, and the like, polyamides, such as Nylon-6, Nylon-66, Nylon 69, Nylon 610, Nylon 611, Nylon 612, Nylon 11, Nylon 12, and copolymers and the like, polyimides, polyphenylene sulfide, polyphenylene oxide, polysulfones, polyethersulfones, rubbers, polycarbonate, polyacrylates, terpene resins, polyacetal, styrene/acrylonitrile copolymers, styrene/maleic anhydride copolymers, styrene/maleimide copolymers, coumarone/indene copolymers, and the like and combinations thereof.
These other polymers may be incorporated within the polyesters which incorporate poly(alkylene ether) glycols of the present invention through a separate melt compounding process utilizing any known intensive mixing process, such as extrusion through a single or twin screw extruder, through intimate mixing with the solid granular material, such as mixing, stirring or pellet blending operations, or through cofeeding within the process. Alternatively, the other polymers may be incorporated into the preformed polyester starting material prior to the process of the present invention. If said other polymers are incorporated prior to or during the process of the present invention, it is important to ensure that they do not interfere with the process of the present invention.
The polyesters which incorporate poly(alkylene ether)glycols produced within the process of the present invention will find utility as elastomers for fibers or molded parts.